Combobox in Editor toolbar won't accept focus

CDC

We recently upgraded from 2016 R2 to the latest 2017 R1 and noticed a change in the editor toolbar behavior. We insert a kendo combobox into the editor toolbar as a custom tool. Prior to upgrading we could click on the combobox, it would allow focus and we could type into the combobox, filtering the list of options. Now when clicking the combobox it does not allow focus. This seems like the editor is preventing focus on-click as we see this behavior for the built it comboboxes (font and font size).

Is this an intended change? If so, how can we allow focus to our combobox? Thanks,

Progress, Telerik, and certain product names used herein are trademarks or registered trademarks of Progress Software Corporation and/or one of its subsidiaries or affiliates in the U.S. and/or other countries. See Trademarks or appropriate markings.